This invention relates to an arrangement for the production of longitudinal screed slabs consisting of concrete.
PCT publication WO 81/02600 published Sept. 17, 1981 describes a method for producing concrete floors of high quality as regards planeness and rational construction. With this invention use is made of slide tracks for the vibrating beams employed in the process of producing the floor, by way of permanent moulds. By providing the slabs with either holes or both holes and brackets continuous reinforcement can be achieved, which means that shrinkage cracks do not arise in the floor along these slabs.
In producing these slabs a number of problems have been encountered, all of which could be solved with the aid of generally known technology (e.g. concrete grades suitable for the hard wear). One problem, however, has proved to be of considerably greater complexity. It relates to the fact that when casting the slabs, which is done in so-called battery moulds, the slabs must be linear. The difficulty consists partly in the fact that it is difficult to produce moulds of sufficient linearity and in that after repeated use the moulds developed a nonlinear shape due to handling. The present invention proposes an arrangement enabling production with the aid of cheap moulds suitable for imparting good linearity to the slabs.
Moulds can be produced from thin metal sheeting bent to the required cross-sectional shape. The sections are then connected by point-welding. This gives rise to heat stresses causing deformation of the sheets with disastrous consequences for the use of the resulting slabs. Also injection-moulded aluminium has been tried but after handling the condition of this product became quite bad. Once this was the case it was less possible to produce correct slabs. In addition aluminium is, after all, subject to the disadvantage that it is attacked by concrete, so that the surface of the product becomes rough.